Vedanta - What Is Consciousness?

In Vedanta, the term used is antakarana, inner instrument, which is different from consciousness. Emotion of happiness comes and goes; I am the same one who felt sad or indifferent. In modern consciousness studies, it's not at all clear. They are still struggling for a definition of consciousness. But in Vedantam, the definition is very clear. It's an operational definition, but very clear definition.